You could try e.g. ffmpeg with the -i switch to find out what's inside. It might only be the container that's unusual, in which case you could simply copy the streams into a better container format. Searching with keywords along those lines landed me on this topic. It's a Linux forum, but all the ffmpeg stuff applies equally on Windows if you can find a proper Windows build.

Intelligent alien life does exist, otherwise they would have contacted us.